Thermo-responsive assembly and methods for making and using the same

ABSTRACT

In an embodiment, an assembly, comprising: a glazing layer; a light absorbing layer; and a thermo-responsive layer between the glazing layer and the light absorbing layer. The thermo-responsive layer comprises a matrix polymer having a glass transition temperature and an inorganic filler, wherein the matrix polymer comprises 0.5 to 10 weight percent of repeat units derived from acrylonitrile, based upon a total weight of the matrix polymer. The refractive indices of the matrix polymer and the inorganic filler differ by less than or equal to 0.05 at 25° C.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 61/780,285 filed Mar. 13, 2013. The relatedapplication is incorporated herein by reference.

BACKGROUND OF THE INVENTION

Disclosed herein are thermo-responsive assemblies that can help controlstagnation temperatures in solar panels used to provide hot water indomestic and commercial entities.

Solar panels can be efficient and cost-effective sources of hot waterfor domestic and commercial hot water heating as well as for spaceheating. Plastic solar panels or modules are commonly constructed from atransparent polymer glazing sheet (e.g., polycarbonate multi-wallsheet), a black plastic absorber sheet with extruded water channels(e.g., polysulfone or polyphenylene ether blend multi-wall sheet), aninsulating backing, and necessary water manifolds and frame pieces.Since the absorber layer is insulated from both the front and back,temperatures much higher than ambient can be attained. Modules arecommonly designed to produce water as hot as 70 degrees Celsius (° C.)to 80° C.

There are sometimes periods in which the module is exposed to the sunand water or other heat transfer fluid is not flowing through theabsorber sheet, and the module can overheat. This is termed “stagnationconditions.” Module temperatures in excess of 140° C. or even 150° C.are possible during these stagnation conditions. During stagnationconditions, the heat deflection temperature of the plastic componentscan be exceeded, resulting in irreversible buckling, thermal expansionbeyond design limits, and/or other thermally-induced effects that canlead to failure of the unit. Using only polymers capable of withstandingsuch temperatures greatly increases the cost of the module. Control ofstagnation temperature therefore is an important design requirement forefficient, cost-effective plastic solar modules.

Accordingly, there is a need for a thermo-responsive assembly that canhelp control stagnation temperatures to provide an efficient,cost-effective plastic solar module.

BRIEF DESCRIPTION

Disclosed herein are thermo-responsive assemblies and methods for makingand using the same.

In an embodiment, an assembly, comprises a glazing layer; a lightabsorbing layer; and a thermo-responsive layer between the glazing layerand the light absorbing layer. The thermo-responsive layer comprises amatrix polymer having a glass transition temperature and an inorganicfiller, wherein the matrix polymer comprises 0.5 to 10 weight percent ofrepeat units derived from acrylonitrile, based upon a total weight ofthe matrix polymer. The refractive indices of the matrix polymer and theinorganic filler differ by less than or equal to 0.05 at 25° C.

In another embodiment, a method of making the assembly comprises aglazing layer; a light absorbing layer; and a thermo-responsive layerbetween the glazing layer and the light absorbing layer, comprises:forming the glazing layer; forming the light absorbing layer; andforming the thermo-responsive layer between the glazing layer and thelight absorbing layer. The thermo-responsive layer comprises a matrixpolymer having a glass transition temperature and an inorganic filler.The refractive indices of the matrix polymer and the inorganic fillerdiffer by less than or equal to 0.05 at 25° C.

These and other features of the assembly and methods of making will beunderstood from the drawings and description below.

BRIEF DESCRIPTION OF THE DRAWINGS

The following is a brief description of the drawings wherein likeelements are numbered alike and which are presented for the purposes ofillustrating the exemplary embodiments disclosed herein and not for thepurposes of limiting the same.

FIG. 1 is a graphical illustration of the refractive index versustemperature of a matrix polymer and a filler.

FIG. 2 is a schematic illustration of a thermo-responsive assembly atnormal use temperatures.

FIG. 3 is a schematic illustration of the thermo-responsive assembly ofFIG. 2 at elevated temperatures above the glass transition temperatureof the materials used in the thermo-responsive assembly.

FIG. 4 is a graphical illustration of the strain versus time of variousmatrix polymers and a filler as described in Example 5.

FIG. 5 is a graphical illustration of viscosity versus shear rate ofvarious matrix polymers and a filler as described in Example 5.

FIG. 6 is a graphical illustration of the reflection versus temperatureof a matrix polymer and a filler as described in Example 6.

DETAILED DESCRIPTION

Disclosed herein are thermo-responsive assemblies comprising athermo-responsive layer comprising a transparent matrix polymer filledwith an inorganic material (i.e., filler). The inorganic material canhave an average particle size of less than 10 micrometers (μm) and amatching refractive index with the matrix polymer (e.g., wherein therefractive indices differ by less than or equal to 0.05 at 25° C.). Thethermo-responsive assemblies as described herein can have little or nochange in the reflection of incident light at temperatures below theglass transition temperature of the matrix polymer, since the refractiveindex of the materials used in the assemblies changes slowly below theglass transition temperature (Tg) of the matrix polymer. Thethermo-responsive assemblies disclosed herein, can however, haveincreased reflection above the glass transition temperature of thematrix polymer. This is because above the Tg, the refractive index ofthe transparent matrix polymer generally decreases rapidly, while therefractive index of the inorganic material remains nearly constant. Theresulting mismatch in the refractive indices can result in somereflection, with, for example, 10% to 20% reflection being sufficient tokeep the thermo-responsive assemblies from buckling or other mechanicalfailures. The term thermo-responsive layer is used herein to refer to alayer that changes its light transmission in response to a temperaturechange.

The thermo-responsive assembly is often used in non-horizontalconfigurations (with respect to the ground). For example, thethermo-responsive assembly can be used as a solar hot water module in anon-horizontal configuration. Since the thermo-responsive layer can beat temperatures greater than its glass transition temperature of thematerial for long enough periods of time, the thermo-responsive layercan experience creep and flow of the material. This creep and flow ofthe material is undesirable as it can result in a thinner material atone end and a thicker material at the other end. It was surprisinglydiscovered that incorporating a relatively small amount, for example,0.5 to 10 weight percent (wt. %), specifically, 1 to 5 wt. %, of repeatunits derived from acrylonitrile in the backbone of the matrix polymercan result in reduced creep. For example, a greater than or equal to 20%reduction, specifically, a 20 to 50% reduction in the extent of creepwas achieved without adversely affecting the processing characteristicsof the thermo-responsive layer.

Mechanical louvers could be made to open at elevated temperatures andthereby open the module to release heat, but this introduces movingparts, increases complexity and cost, and provides an additional failuremechanism. Many concepts using thermo-responsive materials for thermalcontrol rely on, for example, a phase separation process, an abruptphase transition, by strongly differing temperature dependencies of therefractive indices of domains and matrix, and/or a change in theirvisible optical properties to cause scattering of light and attenuatethe amount of light that can reach an absorber layer (e.g., certainhydrogels and polymer blends with critical temperatures for miscibility,liquid crystals, etc.). However, none of these systems seem practical orcost-effective for a low-cost plastic solar module since they involvecomponents that are fluid or involve difficult to tailor chemicalmaterial components.

The thermo-responsive assemblies disclosed herein can comprise a glazinglayer, a thermo-responsive layer, and an absorber layer (e.g., a lightabsorbing layer), wherein the thermo-responsive layer can be between theglazing layer and the absorber layer. The glazing layer and thethermo-responsive layer can generally be transparent (e.g., have greaterthan or equal to 85% transmission in the visible and infrared ranges ofthe electromagnetic spectrum), while the absorber layer can be opaque.The absorber layer can generally be black, meaning that it will not haveany transmission. The absorber layer can absorb incoming light andtransfer the energy to a circulating fluid, such as air, water, ethyleneglycol, etc. The absorber layer can be made of any material withsufficient thermal and hydrolytic stability. Examples includepolysulfones, modified poly(phenylene oxides), polyetheretherketone(PEEK), and polyimide. The glazing layer can comprise a monolithic or amultiwall sheet. When comprising a multiwall sheet, the glazing layercan comprise, for example, a first wall, a second wall, and ribsdisposed therebetween the first wall and the second wall. Additionalwalls (e.g., a third wall, fourth wall, etc.) and additional ribsdispersed therebetween can also be present. The thermo-responsive layercan comprise a matrix polymer and an inorganic filler. The transmissionof a glazing layer can depend on the number of air/polymer interfaces sothat a twin wall sheet will have less transmission than a monolithicsheet and a triple wall sheet even less. The effect of the added layerson the energy reaching the absorber layer can be more than compensatedfor by improved insulation provided by the multiple walls at an optimumnumber of walls.

The mismatch of the refractive indices of the matrix polymer andinorganic filler at temperatures above the Tg of the matrix polymer canprovide reflection of the incoming light, which, during stagnationperiods, can reduce the temperature extremes experienced by thethermo-responsive assembly, thereby resulting in a lower likelihood offailure (e.g., buckling, warping, thermal expansion, etc.) of the othercomponents of the thermo-responsive assembly. Stated another way, thethermo-responsive assemblies disclosed herein can provide protection tothe various other components of the thermo-responsive assembly (i.e.,panels (e.g., solar panels)) against failure or damage due to exposureto temperatures above the heat deflection temperature of the components.The thermo-responsive layer can be attached (e.g., laminated,co-extruded, dispersed across) the glazing layer and/or the absorberlayer. An air gap can be present between the thermo-responsive layer andthe absorber layer.

As previously mentioned, a thermo-responsive layer comprising atransparent polymer (i.e., matrix polymer) and an inorganic material(i.e., filler) having an average particle size less than or equal to 10μm and a matching refractive index with the matrix polymer (e.g.,wherein the refractive indices differ by less than or equal to 0.05 at25° C., specifically, less than or equal to 0.01 at 25° C.) candemonstrate little or no change in the reflection of incident light attemperatures below the Tg of the matrix polymer. Although not wishing tobe bound by theory, it is believed this occurs because the refractiveindex of both materials changes relatively slowly below the Tg. However,above the Tg, the density and hence, the refractive index of the matrixpolymer can change rapidly, while the refractive index of the inorganicfiller can continue to change very slowly. This can result in anincreasingly large refractive index mismatch between the matrix polymerand the filler, which can in turn cause some light to be reflected asshown schematically in FIG. 1. For example, as illustrated in FIG. 1,the matrix polymer 10 and filler 12 can have the same refractive index16 below the Tg 14, which can give high transmission. Above the Tg 14,however, the refractive indices can be mismatched illustrated by line18, resulting in reflection. Thus, the amount of light transmittedthrough the thermo-responsive layer (e.g., light control layer) can bereduced to an increasing degree above Tg, which can lead to a decreasein the stagnation temperatures experienced by the components of thepanel.

For example, as shown in FIG. 2, a thermo-responsive assembly 20 isillustrated that can comprise a glazing layer 22, a thermo-responsivelayer 24, and an absorber layer 26. The glazing layer 22 can comprise asolid sheet, a multilayer sheet, or a multiwall sheet. A multiwall sheethaving a first wall 34, a second wall 36, and ribs 38 locatedtherebetween is illustrated in FIGS. 2 and 3. The first wall 34 can havea first wall first surface 40 and a first wall second surface 42, whilethe second wall 36 can have a second wall first surface 44 and a secondwall second surface 46. The absorber layer 26 can comprise an absorberlayer first surface 48 and an absorber layer second surface 50. An airgap 52 can be present between the thermo-responsive layer 24 and theabsorber layer 26. When the thermo-responsive assembly 20 is exposed tonormal use temperatures, the thermo-responsive assembly 20 canexperience little or no reflection of the incoming light 28 by thethermo-responsive layer 24. Some haze or forward scattering 30 can beexperienced and is acceptable because as shown in FIG. 2, the lightstill reaches the absorber layer 26. At elevated temperatures above theTg of the matrix polymer, as shown in FIG. 3, there is increasedscattering 30 and reflection 32, so that less incoming light 28 reachesthe absorber layer 26. Since the absorber layer 26 can be partiallyshaded as shown in FIG. 3, the temperature rise of the thermo-responsiveassembly 20 can be attenuated.

The thermo-responsive layer 24 can be firmly attached to the glazinglayer 22 and/or the absorber layer 26, with either or both of theglazing layer 22 and the absorber layer 26 providing mechanical supportfor the thermo-responsive layer 24, since the thermo-responsive layer 24generally becomes mechanically weak at temperatures above the Tg. Forexample, the thermo-responsive layer 24 can be co-extruded with theabsorber layer 26 or with the glazing layer 22 or can be laminated ontothe absorber layer 26 or the glazing layer 22. The location of thethermo-responsive layer 24 is not limited and can generally be in anylocation within the thermo-responsive assembly 20. For example, thethermo-responsive layer 24 can be located on the first wall firstsurface 40, first wall second surface 42, second wall first surface 44,the second wall second surface 46, or the absorber layer first surface48. It is not generally desirable for the thermo-responsive layer 24 tobe on the absorber layer second surface 50 because no light reaches theabsorber layer second surface 50. It can generally be desirable for thethermo-responsive layer 24 to be dispersed across the second wall secondsurface 46 as shown in FIG. 3.

The Tg of the matrix polymer used in the thermo-responsive layer can beadjusted to be approximately equal to the temperature attained duringnormal working conditions, for example, with the use of plasticizers inthe thermo-responsive layer. The polymer used in the thermo-responsivelayer can also be selected on the basis of the Tg being approximatelyequal to the temperature attained during normal working conditions; forexample, difference between the Tg of the polymer and the normal workingconditions can be less than or equal to 20° C., or less than or equal to15° C., or less than or equal to 10° C., and preferably less than orequal to 5° C.). It is also desirable that the Tg of the polymer begreater than the temperature at the normal working conditions. In someapplications, the normal working conditions can be 50° C. to 70° C.Therefore, if the temperature at the normal working conditions of 50°C., the Tg of the polymer can be 30° C. to 70° C., and is desirably 50°C. to 70° C.

The Tg of the polymer can be, for example, greater than or equal to 25°C. and less than or equal to 100° C., specifically, the Tg can be 50° C.to 100° C., more specifically, 60° C. to 90° C., and even morespecifically, 65° C. to 85° C. The refractive indices of the matrixpolymer and the filler can be any value as long as they are matched±0.05 at 25° C., for example, the refractive index of the matrix can be1.4 to 1.75, specifically, 1.45 to 1.7, and more specifically, 1.47 to1.59. Aliphatic methacrylates generally have a refractive index of 1.47,polycarbonate generally has a refractive index of 1.58, and polystyrenegenerally has a refractive index of 1.59. In general, it can bedesirable for the refractive index of the polymer and the refractiveindex of the inorganic filler to match to within 0.05, specifically,within 0.01, and more specifically, within 0.005, at 25° C. However, ifthe refractive index cannot be matched, it can be desirable for therefractive index of the polymer to be 0.005 to 0.02 less than that ofthe filler.

Possible polymeric resins that can be employed for the matrix polymerused in the thermo-responsive layer can comprise any transparenthomopolymer, copolymer, or blend thereof. It can be desirable for thematrix polymer to have optical transparency, a Tg within the desiredrange (with or without the use of plasticizers), and stability towardlight and heat. Examples of desirable polymers include polyesters,polycarbonates, polystyrene, poly(methyl methacrylate) (PMMA),poly(ethyl methacrylate), poly(butyl methacrylate),poly(styrene-co-methyl methacrylate), poly(styrene-co-acrylonitrile)(SAN), poly(methyl methacrylate-co-styrene-co-acrylonitrile) (MMASAN),and other copolymers of styrene, acrylonitrile, various (meth)acrylicacids, and various (meth)acrylates, as well as combinations comprisingat least one of the foregoing. For example, the matrix polymer cancomprise PMMA or can comprise a combination of PMMA and SAN and/or thematrix polymer can comprise a combination of two or more of PMMA, SAN,and poly(butyl methacrylate). The matrix polymer can be selected suchthat the Tg is in the desired range or can be brought within the desiredrange with the help of additives such as plasticizers. Desirably, therefractive index of the matrix polymer will approximately match or havea value slightly less than the refractive index of the filler (e.g., bewithin 0.005 to 0.02) at normal working temperatures so that the totalforward transmission of the glazing layer plus the thermo-responsivelayer is greater than 80%. Forward transmission generally refers to alllight emanating from the non-irradiated surface of the article, i.e.,all light that is not reflected, absorbed, or going out the edges.Forward transmission includes both direct transmission along the normalline as well as any light scattered off-normal (haze). Measurement oftotal forward transmission (or total reflection) is usually accomplishedwith the use of a spectrometer equipped with an integrating sphere.

It was surprisingly discovered that incorporating relatively smallamounts, for example, 0.5 to 10 wt. %, specifically, 1 to 5 wt. % ofrepeat units derived from acrylonitrile in the backbone of the matrixpolymer can result in creep reduction, e.g., a greater than or equal to20% reduction, specifically, a 20 to 50% reduction in the extent ofcreep. Specifically, the matrix polymer can comprise a copolymercomprising 0.5 to 10 wt. %, specifically, 1 to 5 wt. % of acrylonitrilebased on the total weight of the matrix polymer. The matrix polymer canfurther comprise 90 to 99.5 wt. %, specifically, 95 to 99 wt. % of anyof the other aforementioned matrix polymers based on the total weight ofthe matrix polymer. For example, the matrix polymer can comprise acopolymer comprising 0.5 to 10 wt. % of polyacrylonitrile repeat unitsbased on the total weight of the matrix polymer and 90 to 99.5 wt. %, ofa polystyrene and/or polyacrylate repeat units based on the total weightof the matrix polymer. The polyacrylate can be, for example,polymethacrylate, poly(methyl methacrylate), poly(ethyl methacrylate),poly(butyl methacrylate), or a combination comprising one or more of theforegoing. When the matrix polymer comprises polystyrene andpolyacrylate repeat units, the ratio of polystyrene to polyacrylate canbe 10:1 to 1:10, specifically, 6:1 to 1:1, more specifically, 5:1 to3:1.

The acrylonitrile can be randomly dispersed throughout the matrixpolymer backbone, where the resulting copolymer can be polymerized byfree-radical polymerization of the respective monomers. The weightaverage molecular weight, Mw, of the matrix polymer can be 10 to 300kilograms per mole (kg/mol), specifically, 50 to 200 kg/mol asdetermined by gel permeation chromatography (GPC) based on polycarbonatestandards. The number average molecular weight, Mn, of the matrixpolymer can be 5 to 300 kilograms per mole (kg/mol), specifically, 20 to150 kg/mol as determined by gel permeation chromatography (GPC) based onpolycarbonate standards.

The thermo-responsive layer or matrix polymer can also include variousadditives ordinarily incorporated into polymer compositions of thistype, with the proviso that the additive(s) are selected so as to notsignificantly adversely affect the desired properties of thethermo-responsive layer, in particular, the ability of thethermo-responsive layer to reflect incoming light. Examples of additivesthat can be included in the matrix polymer or the thermo-responsivelayer include optical effects fillers, impact modifiers, fillers,reinforcing agents, antioxidants, heat stabilizers, light stabilizers,ultraviolet (UV) light stabilizers, plasticizers, lubricants, moldrelease agents, antistatic agents, colorants (such as carbon black andorganic dyes), surface effect additives, radiation stabilizers (e.g.,infrared absorbing), gamma stabilizer, flame retardants, and anti-dripagents. A combination of additives can be used, for example, acombination of a heat stabilizer, mold release agent, and ultravioletlight stabilizer. In general, the additives are used in the amountsgenerally known to be effective. Each of these additives can be presentin amounts of 0.0001 to 10 wt. %, based on the total weight of thethermo-responsive layer.

For example, plasticizing agents can be used to adjust the Tg and therefractive index and additives such as antioxidants and lightstabilizers can also be present in the matrix polymer orthermo-responsive layer. Plasticizers for inclusion in the matrixpolymer and/or thermo-responsive layer can include benzoate esters ofpolyols such as penterythritol tetrabenzoate, aliphatic esters, and arylesters of phosphates such as resorcinol bis(diphenyl phosphate), as wellas combinations comprising at least one of the foregoing. When thethermo-responsive layer comprises, for example, a poly(styrene-co-butylmethacrylate) copolymer, the layer can be free of, i.e., can comprise 0wt. % of a plasticizer such as resorcinol bis(diphenyl phosphate).

The matrix polymer or thermo-responsive layer can further optionallyinclude a flame retardant. Flame retardants include organic and/orinorganic materials. Organic compounds include, for example, phosphorus,sulphonates, and/or halogenated materials (e.g., comprising brominechlorine, and so forth, such as brominated polycarbonate).Non-brominated and non-chlorinated phosphorus-containing flame retardantadditives can be preferred in certain applications for regulatoryreasons, for example, organic phosphates and organic compoundscontaining phosphorus-nitrogen bonds.

Inorganic flame retardants include, for example, C₁₋₁₆ alkyl sulfonatesalts such as potassium perfluorobutane sulfonate (Rimar salt),potassium perfluorooctane sulfonate, tetraethyl ammonium perfluorohexanesulfonate, and potassium diphenylsulfone sulfonate (e.g., KSS); saltssuch as Na₂CO₃, K₂CO₃, MgCO₃, CaCO₃, and BaCO₃, or fluoro-anioncomplexes such as Li₃AlF₆, BaSiF₆, KBF₄, K₃AlF₆, KAlF₄, K₂SiF₆, and/orNa₃AlF₆. When present, inorganic flame retardant salts are present inamounts of 0.01 to 10 parts by weight, more specifically, 0.02 to 1parts by weight, based on 100 parts by weight of the thermo-responsivelayer.

Light stabilizers and/or ultraviolet light (UV) absorbing stabilizerscan also be used. Exemplary UV light absorbing stabilizers includehydroxybenzophenones; hydroxybenzotriazoles; hydroxyphenyl triazines(e.g., 2-hydroxyphenyl triazines); cyanoacrylates; oxanilides;benzoxazinones; dibenzoylresorcinols;2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)-phenol (CYASORB™5411); 2-hydroxy-4-n-octyloxybenzophenone (CYASORB™ 531);2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)-phenol(CYASORB™ 1164); 2-[4,6-diphenyl-1.3.5-triazin-2-yl]-5-(hexyloxy)-phenol(Tinuvin 1577), 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one)(CYASORB™ UV-3638);1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane(UVINUL™ 3030); 2,2′-(1,4-phenylene)bis(4H-3,1-benzoxazin-4-one);1,3-bis[(2-cyano-3,3-diphenylacryloyl)oxy]-2,2-bis[[(2-cyano-3,3-diphenylacryloyl)oxy]methyl]propane;4,6-dibenzoylresorcinol, nano-size inorganic materials such as titaniumoxide, cerium oxide, and zinc oxide, all with an average particle sizeof less than or equal to 100 nanometers, or combinations comprising atleast one of the foregoing UV light absorbing stabilizers. UV lightabsorbing stabilizers are used in amounts of 0.01 to 5 parts by weight,based on 100 parts by weight of the total composition, excluding anyfiller.

Anti-drip agents can also be used in the matrix polymer orthermo-responsive layer, for example, a fibril forming fluoropolymersuch as polytetrafluoroethylene (PTFE). The anti-drip agent can beencapsulated by a rigid copolymer, for example, styrene-acrylonitrilecopolymer (SAN). PTFE encapsulated in SAN is known as TSAN. An exemplaryTSAN comprises 50 wt. % PTFE and 50 wt. % SAN, based on the total weightof the encapsulated fluoropolymer. The SAN can comprise, for example, 75wt. % styrene and 25 wt. % acrylonitrile based on the total weight ofthe copolymer. Anti-drip agents can be used in amounts of 0.1 to 10parts by weight, based on 100 parts by weight of the total compositionof the particular layer, excluding any filler.

Any inorganic filler can be used in the thermo-responsive layer,however, as previously described herein, it can be desirable for therefractive index of the filler to match the refractive index of thematrix polymer (e.g., be within 0.01 of one another) or for therefractive index of the matrix polymer to be 0.005 to 0.02 less than therefractive index of the filler. Generally, the average particle size canbe less than or equal to 10 micrometers (μm), specifically, less than orequal to 7.5 μm, more specifically, less than or equal to 5 μm, and evenmore specifically, less than or equal to 2 μm. Examples of fillersinclude, but are not limited to, silica, quartz, glass, ceramicparticles, gypsum, feldspar, calcium silicate, barium metaborate, mica,clays, magnesium hydroxide, aluminum trihydroxide, Fuller's earth,calcium hydroxide, pyrophyllite, talc, zinc borate, and combinationscomprising at least one of the foregoing. Desirable fillers can havehigh purity and a single component with a well-defined refractive index.Examples of such fillers include, but are not limited to glass,magnesium hydroxide, silica and quartz.

The amount of light reflected above the Tg of the filler can depend onthe loading of the filler, the particle size of the filler, thethickness of the thermo-responsive layer, and the amount of refractiveindex mismatch between the filler and the polymer matrix. For example,the thickness of the thermo-responsive layer can be 25 μm to 2,500 μm (1mil to 100 mils), specifically, 100 μm to 1,250 μm (4 mils to 50 mils),and more specifically, 250 μm to 1,000 μm (10 mils to 40 mils). Thefiller can be present in the thermo-responsive layer in amounts of 5 wt.% to 80 wt. %, specifically, 10 wt. % to 60 wt. %, and morespecifically, 20 wt. % to 60 wt. %. For example, the thermo-responsivelayers disclosed herein comprising a matrix polymer and inorganic fillercan have a reflection of greater than or equal to 10% when exposed totemperatures above the Tg of the matrix polymer at a thickness of 25 μmto 2500 μm.

The thermo-responsive layer can be fabricated by any means includingsolvent casting, melt casting, extrusion, blow molding, or co-extrusiononto a substrate. For example, the co-extruded substrate can be asurface of the glazing layer (e.g., the second wall second surface)and/or can be a surface of the absorber layer (e.g., the absorber layerfirst surface. If fabricated separately, the thermo-responsive layer canbe laminated onto the glazing layer or the absorber layer with orwithout an adhesive layer (e.g., a tie layer).

The thickness of the thermo-responsive assembly can vary depending uponthe thickness of the individual components of the thermo-responsiveassembly. For example, the glazing layer can comprise a monolithic(e.g., one wall) sheet or a multiwall sheet (e.g., comprising greaterthan one wall with greater than one air channel (e.g., rib) locatedtherebetween). Generally, the thickness of the glazing layer can be lessthan or equal to 55 millimeters (mm), specifically, 4 mm to 55 mm, morespecifically, 2 mm to 35 mm, even more specifically, 1 mm to 25 mm, andstill more specifically, 0.5 mm to 20 mm, as well as any and all rangesand endpoints located therebetween. For example, for a multiwall sheet,the total thickness can be 4 mm to 55 mm, while for a monolithic sheet,the total thickness can be 0.5 mm to 20 mm. The thickness of thethermo-responsive layer can be 25 μm to 2,500 μm, specifically, 100 μmto 1,250 μm, and more specifically, 250 μm to 1,000 μm, while thethickness of the absorber layer can be 1 mm to 55 mm, specifically, 2 mmto 35 mm, more specifically, 2 mm to 25 mm, and even more specifically,3 mm to 15 mm.

Transparency can be desired at temperatures lower than the Tg of thethermo-responsive layer. Percent transmission for laboratory scalesamples can be determined using ASTM D1003-00, Procedure B using CIEstandard illuminant C. ASTM D-1003-00 (Procedure B, Spectrophotometer,using illuminant C with diffuse illumination with unidirectionalviewing) defines transmittance as:

$\begin{matrix}{{\% \mspace{14mu} T} = {\left( \frac{I}{I_{o}} \right) \times 100\%}} & (1)\end{matrix}$

wherein:

-   -   I=intensity of the light passing through the test sample    -   I_(o)=Intensity of incident light.

Compared to an assembly of a glazing layer without a thermo-responsivelayer, an assembly of glazing layer with a thermo-responsive layer, attemperatures below the Tg of a matrix polymer of the thermo-responsivelayer can decrease the total transmission (i.e., direct+diffuse) by lessthan or equal to 5%, specifically, by less than or equal to 3%, and morespecifically, by less than or equal to 2%. The glazing layer and/or thethermo-responsive layer can also desirably have an ultraviolet lightstability of 20 years such that they retain greater than or equal to 80%of their light transmission capabilities over that 20 year period.

The thermo-responsive assemblies can likewise be used in any applicationwhere, for example, it is desirable to regulate temperature based onlight reflection (such as in solar panels, in photovoltaic applications(e.g., photovoltaic cell), and in greenhouse applications (e.g.,greenhouse roof)). The thermo-responsive layer can be applied to a glassand/or to a plastic window (such as a vehicle window and a buildingwindow, for example, a greenhouse, an office, and a house).

The thermo-responsive assemblies as described herein are furtherillustrated by the following non-limiting examples.

EXAMPLES Example 1 Preparation of a Matrix Terpolymer 1

80 milliliters (mL) of toluene (Fisher, optima grade); 64 grams (g) (614mmol) of styrene (Aldrich, purified by distillation); 17.5 g (123millimole (mmol)) of n-butyl methacrylate (Aldrich, purified bydistillation); 0.815 g (15 mmol) of acrylonitrile (Aldrich); and 150milligrams (mg) (0.913 mmol) azobisisobutyronitrile (AIBN) (Aldrich,recrystallized from methanol) were added to a 250 mL round-bottomedflask equipped with a nitrogen diffusion tube, mechanical stirring, areflux condenser, and thermocouple. The flask was sealed allowing onlynitrogen in through the diffusion tube and gasses out through thecondenser and then through a silicone oil bubbler. A stream of nitrogenwas bubbled through the round-bottomed flask below the surface of thesolution to remove oxygen for 30 minutes then the nitrogen tube wasraised out of the solution and the rate of nitrogen purge reduced to avery slow bubble. The temperature was then brought to 60° C. Thereaction was heated for two days and then allowed to cool to roomtemperature. Once cooled, the contents of the flask were transferred toan addition funnel and the flask was rinsed twice with 100 mL ofchloroform. The chloroform solution was added to the addition funnel andshaken, homogenizing the solution. The polymer was precipitated byslowly adding 100 mL of the chloroform solution to 500 mL of methanol ina rapidly stirred blender. The precipitate was collected by vacuumfiltration and rinsed with fresh methanol. This was repeated until allthe chloroform solution was precipitated. The polymer was dissolved in250 mL of chloroform and precipitated again. A third precipitation wasdone to remove as much unreacted monomer and toluene as possible beforedrying in a vacuum oven at 40° C. or less for three days. Thispolymerization resulted in a 1 wt. % acrylonitrile copolymer with an Mwof 93 kilograms per mole (kg/mol) as determined by GPC based onpolycarbonate standards.

Examples 2-4 Preparation of Matrix Terpolymers 2-4

The polymerization method of Example 1 was repeated to polymerize matrixpolymers of varying amounts of acrylonitrile and molecular weights,where the resulting amounts of acrylonitrile, the Mw, the Mn, and the Tgcan be seen in Table 1.

TABLE 1 Matrix terpolymer 1 2 3 4 Acrylonitrile (wt. %) 1 1 5 0 Mw(kg/mol) 93 133 143 152 Mn (kg/mol) 32 62 78 74 Tg (° C.) 79 78 77 81

Example 5 Rheological Properties of Terpolymers 1-4

The rheological properties were determined by first preparingcorresponding filled terpolymer samples 1-4 comprising 50 wt. % of afiller. Specifically, five grams of matrix polymer were dissolved in 20mL of chloroform in a 100 milliliter plastic beaker. 5 g of Mg(OH)₂filler were added and mixed in a high sheer mixer for 5 minutes. Theresulting solution was then poured into two aluminum tins and driedfirst on a warm plate at ambient pressure then dried in a vacuum ovenfor 15 hours at 50° C. The dried resin was the removed from the pans andcrushed into a powder. The samples were then vacuum dried at 50° C. fora minimum of 20 hours. They were then compression molded into 25 mmdiameter by approximately 2 mm thick disks at a temperature ofapproximately 130° C. After molding, they were returned to a 50° C.vacuum oven to maintain dryness until they were used.

Creep measurements were performed on the filled terpolymer samples byapplying a fixed stress to a sample and monitoring the resultingdeformation or strain with time using a TA Instruments AR G2 rheometerequipped with nitrogen purged oven and 25 mm diameter parallel plates.The measurements were done at 140° C. in shear using an applied stressof 20 Pascals (Pa), where the results can be seen FIG. 4.

FIG. 4 shows that the deformation with time, i.e., the extent of creep,is significantly reduced in filled terpolymer samples 1-3 that compriseacrylonitrile repeat units relative to the filled terpolymer sample 4that did not comprise acrylonitrile repeat units. The fact that thecoatings ultimately reach constant strain values, as indicated by thedashed lines in FIG. 4, indicates that they have a yield stress greaterthan the applied stress of 20 Pa. It is believed that a yield stress ofgreater than 20 Pa should be adequate to prevent the coatings fromexhibiting creep when used in the thermo-responsive layer, provided thecoating is not overly thick. The reduced creep exhibited by filledterpolymer samples 1-3 indicates that they are more robust, andtherefore are able to tolerate more abusive conditions. While the strainappears to resume increasing for filled terpolymer sample 2 aftermaintaining a plateau value at intermediate times, it is noted that themeasured strain values are still significantly lower than those ofcontrol sample 4 and are in fact lowest values measured at all timesrelative to all of the samples measured.

It is further noted that the results in FIG. 4 that show thatcompositions containing acrylonitrile exhibit both reduced creep andreduced terminal strain values are further surprising considering thelower molecular weight values of the matrix terpolymers 1-3 relative tothe control copolymer, matrix terpolymer 4.

Viscosity measurements at 140° C. were further performed on filledterpolymer samples 3 and 4, where the viscosity in poise (P) is shownversus shear rate in 1/seconds (s⁻¹) in FIG. 5. FIG. 5 shows that theimprovements in the creep properties of the acrylonitrile containingsample occurs without a corresponding increase in the coating viscosity.In other words, the similar viscosities indicate that improved creepresistance is obtained without paying a penalty in the ability toprocess the coatings.

Example 5 Reflectivity Properties of Filled Terpolymer Sample 2

In order to determine the effect of acrylonitrile in the copolymer onthe optical performance of the thermo-responsive layer, the change inreflectivity versus temperature was measured. The sample was prepared byplacing approximately 1.6 g of the filled terpolymer sample 2 in ashimmed compression mold backed with Ferrotype plates, heating toapproximately 160° C. in a Carver press for 5 minutes at 4 tons (3.6×10³kilograms) of pressure, and then allowing the sample to cool toapproximately 60° C. under pressure. This resulted in a disk 2 inches(5.1 cm) in diameter that was 20 mils (508 micrometers) thick. The diskwas then laminated to a 10 mil (254 micrometers) thick polycarbonatefilm by the same procedure in order to provide extra support during thethermal testing.

FIG. 6 shows the % reflection values over the range of 30 to 130° C.,where there was an increase in the reflectivity of 15.3% from 14.3% to29.6%. These results compared favorably to a sample prepared with noacrylonitrile which showed an equivalent change in reflectivity of 14.8%over the same temperature range.

It is to be understood that the matrix polymer and inorganic filler isnot limited to those disclosed herein and used in the examples. Oneskilled in the art will readily be able to select a polymer for thematrix polymer and based upon the refractive index of that polymer chosethe inorganic filler accordingly.

Set forth below are some embodiments of connectors and methods of makingconnectors as disclosed herein.

Embodiment 1: an assembly, comprising: a glazing layer; a lightabsorbing layer; and a thermo-responsive layer between the glazing layerand the light absorbing layer. The thermo-responsive layer comprises amatrix polymer having a glass transition temperature and an inorganicfiller having an average particle size. The matrix polymer comprises 0.5to 10 weight percent of repeat units derived from acrylonitrile, basedupon a total weight of the matrix polymer, wherein the refractiveindices of the matrix polymer and the inorganic filler differ by lessthan or equal to 0.05 at 25° C.

Embodiment 2: the assembly of Embodiment 1, wherein matrix polymercomprises 1 to 5 weight percent of repeat units derived fromacrylonitrile.

Embodiment 3: the assembly of any of Embodiments 1-2, wherein matrixpolymer further comprises polystyrene and/or polyacrylate repeat units.

Embodiment 4: the assembly of Embodiment 3, wherein the polyacrylatecomprises polymethacrylate, poly(methyl methacrylate), poly(ethylmethacrylate), poly(butyl methacrylate), or a combination comprising oneor more of the foregoing.

Embodiment 5: the assembly of any of Embodiments 3-4, wherein the ratioof polystyrene to polyacrylate is 10:1 to 1:10.

Embodiment 6: the assembly of any of Embodiments 3-5, wherein the ratioof polystyrene to polyacrylate is 6:1 to 1:1.

Embodiment 7: the assembly of any of Embodiments 1-6, wherein the glasstransition temperature is 25° C. to 100° C.

Embodiment 8: the assembly of any of Embodiments 1-7, wherein the glasstransition temperature is 60° C. to 90° C.

Embodiment 9: the assembly of any of Embodiments 1-8, wherein the glasstransition temperature is 65° C. to 85° C.

Embodiment 10: the assembly of any of Embodiments 1-9, wherein theparticle size is less than or equal to 10 micrometers.

Embodiment 11: the assembly of Embodiment 10, wherein the particle sizeis less than or equal to 5 micrometers.

Embodiment 12: the assembly of Embodiment 11, wherein the particle sizeis less than or equal to 2 micrometers.

Embodiment 13: the assembly of any of Embodiments 1-12, wherein thematrix polymer refractive index is 1.4 to 1.75.

Embodiment 14: the assembly of any of Embodiments 1-13, wherein therefractive indices of the inorganic filler and the matrix polymer differby less than or equal to 0.01 at 25° C.

Embodiment 15: the assembly of any of Embodiments 1-14, wherein theglazing layer comprises a multiwall sheet comprising a first wall, asecond wall, and ribs disposed therebetween. The first wall has a firstwall first surface and a first wall second surface, and the second wallhas a second wall first surface and a second wall second surface. Thethermo-responsive layer is attached to the second wall second surface.

Embodiment 16: the assembly of any of Embodiments 1-15, wherein an airgap is present between the thermo-responsive layer and the lightabsorbing layer.

Embodiment 17: the assembly of any of Embodiments 1-16, wherein thematrix polymer has greater than or equal to 85% transparency measuredaccording to ASTM D1003-00.

Embodiment 18: the assembly of any of Embodiments 1-17, wherein thematrix polymer comprises polyesters, polycarbonates, polystyrene,poly(methyl methacrylate), poly(ethyl methacrylate),poly(styrene-co-methyl methacrylate), poly(styrene-co-acrylonitrile),poly(methyl methacrylate-co-styrene-co-acrylonitrile), copolymers ofstyrene, acrylonitrile, (meth)acrylic acids, and (meth)acrylates, andcombinations comprising at least one of the foregoing.

Embodiment 19: the assembly of any of Embodiments 1-18, wherein thematrix polymer comprises poly(methyl methacrylate),poly(styrene-co-acrylonitrile), or a combination comprising at least oneof the foregoing.

Embodiment 20: the assembly of any of Embodiments 1-19, wherein thethermo-responsive layer further comprises a plasticizer.

Embodiment 21: the assembly of Embodiment 20, wherein the plasticizercomprises benzoate esters, aliphatic esters, aryl esters of phosphates,and combinations comprising at least one of the foregoing.

Embodiment 22: the assembly of Embodiment 21, wherein the plasticizercomprises penterythritol tetrabenzoate, resorcinol bis(diphenylphosphate), and combinations comprising at least one of the foregoing.

Embodiment 23: the assembly of any of Embodiments 1-22, wherein thefiller comprises silica, quartz, glass, ceramic particles, gypsum,feldspar, calcium silicate, barium metaborate, mica, clays, magnesiumhydroxide, aluminum trihydroxide, Fuller's earth, calcium hydroxide,pyrophyllite, talc, zinc borate, and combinations comprising at leastone of the foregoing.

Embodiment 24: the assembly of any of Embodiments 1-23, wherein thefiller comprises magnesium hydroxide.

Embodiment 25: the assembly of any of Embodiments 1-23, wherein thefiller comprises glass.

Embodiment 26: the assembly of any of Embodiments 1-25, wherein thefiller is present in an amount of 5% to 80% by weight.

Embodiment 27: the assembly of any of Embodiments 1-26, wherein thethermo-responsive layer, having a thickness of 25 μm to 2,500 μm, hasgreater than or equal to 10% reflection when exposed to temperaturesgreater than a glass transition temperature of the matrix polymer.

Embodiment 28: a method of making the assembly of any of Embodiments1-27, comprising: forming the glazing layer; forming the light absorbinglayer; and forming the thermo-responsive layer, wherein thethermo-responsive layer is between the glazing layer and the lightabsorbing layer. The thermo-responsive layer comprises a matrix polymerhaving a glass transition temperature and an inorganic filler having anaverage particle size, wherein the matrix polymer comprises 0.5 to 10weight percent of repeat units derived from acrylonitrile, based upon atotal weight of the matrix polymer, wherein the refractive indices ofthe matrix polymer and the inorganic filler differ by less than or equalto 0.05 at 25° C.

Embodiment 29: a method of making an assembly, comprising: determining anormal working temperature of the assembly; forming a glazing layer;forming a light absorbing layer; choosing a matrix polymer so that adifference between a glass transition temperature of the matrix polymerand the normal working temperature is less than or equal to 20° C.; andforming a thermo-responsive layer, wherein the thermo-responsive layeris between the glazing layer and the light absorbing layer. Thethermo-responsive layer comprises the matrix polymer and an inorganicfiller, and wherein the refractive indices of the matrix polymer and theinorganic filler differ by less than or equal to 0.05 at 25° C.

Embodiment 30: the method of Embodiment 29, wherein the matrix polymercomprises 0.5 to 10 weight percent of repeat units derived fromacrylonitrile, based upon a total weight of the matrix polymer.

Embodiment 31: the method of any of Embodiments 28-29, furthercomprising co-extruding the glazing layer and the thermo-responsivelayer.

Embodiment 32: the method of any of Embodiments 28-29, furthercomprising laminating the thermo-responsive layer to a surface of theglazing layer.

Embodiment 33: the method of any of Embodiments 28-32, furthercomprising co-extruding the light absorbing layer and thethermo-responsive layer.

Embodiment 34: the method of any of Embodiments 28-32, furthercomprising laminating the thermo-responsive layer to a surface of thelight absorbing layer.

Embodiment 35: the method of any of Embodiments 28-32, wherein theassembly is a solar panel.

Embodiment 36: the method of any of Embodiments 28 and 30-35, furthercomprising determining a normal working temperature of the assembly, andchoosing the matrix polymer so that a difference between the glasstransition temperature and the normal working temperature is less thanor equal to 20° C.

Embodiment 37: an article comprising the assembly of any of Embodiments28-36.

Embodiment 38: the article of Embodiment 37, wherein the article is awindow.

Embodiment 39: the article of Embodiment 37, wherein the article is usedin photovoltaic applications and/or in a greenhouse applications.

All ranges disclosed herein are inclusive of the endpoints, and theendpoints are independently combinable with each other (e.g., ranges of“up to 25 wt. %, or, more specifically, 5 wt. % to 20 wt. %”, isinclusive of the endpoints and all intermediate values of the ranges of“5 wt. % to 25 wt. %,” etc.). “Combination” is inclusive of blends,mixtures, alloys, reaction products, and the like. Furthermore, theterms “first,” “second,” and the like, herein do not denote any order,quantity, or importance, but rather are used to determine one elementfrom another. The terms “a” and “an” and “the” herein do not denote alimitation of quantity, and are to be construed to cover both thesingular and the plural, unless otherwise indicated herein or clearlycontradicted by context. The suffix “(s)” as used herein is intended toinclude both the singular and the plural of the term that it modifies,thereby including one or more of that term (e.g., the film(s) includesone or more films). Reference throughout the specification to “oneembodiment”, “another embodiment”, “an embodiment”, and so forth, meansthat a particular element (e.g., feature, structure, and/orcharacteristic) described in connection with the embodiment is includedin at least one embodiment described herein, and may or may not bepresent in other embodiments. In addition, it is to be understood thatthe described elements may be combined in any suitable manner in thevarious embodiments.

The average particle size can refer to the average a length measuredmaximum axis of each of the particles.

All cited patents, patent applications, and other references areincorporated herein by reference in their entirety. However, if a termin the present application contradicts or conflicts with a term in theincorporated reference, the term from the present application takesprecedence over the conflicting term from the incorporated reference.

While particular embodiments have been described, alternatives,modifications, variations, improvements, and substantial equivalentsthat are or may be presently unforeseen may arise to applicants orothers skilled in the art. Accordingly, the appended claims as filed andas they may be amended are intended to embrace all such alternatives,modifications variations, improvements, and substantial equivalents.

I/We claim:
 1. An assembly, comprising: a glazing layer; a lightabsorbing layer; and a thermo-responsive layer between the glazing layerand the light absorbing layer, wherein the thermo-responsive layercomprises a matrix polymer having a glass transition temperature and aninorganic filler, wherein the matrix polymer comprises 0.5 to 10 weightpercent of repeat units derived from acrylonitrile, based upon a totalweight of the matrix polymer, wherein the refractive indices of thematrix polymer and the inorganic filler differ by less than or equal to0.05 at 25° C.
 2. The assembly of claim 1, wherein the matrix polymercomprises 1 to 5 weight percent of repeat units derived fromacrylonitrile.
 3. The assembly of claim 1, wherein the matrix polymerfurther comprises polystyrene and/or polyacrylate repeat units.
 4. Theassembly of claim 3, wherein the polyacrylate comprisespolymethacrylate, poly(methyl methacrylate), poly(ethyl methacrylate),poly(butyl methacrylate), or a combination comprising one or more of theforegoing.
 5. The assembly of claim 3, wherein the ratio of polystyreneto polyacrylate is 10:1 to 1:10.
 6. The assembly of claim 1, wherein theglass transition temperature is 25° C. to 100° C.
 7. The assembly ofclaim 1, wherein the filler has an average particle size that is lessthan or equal to 10 micrometers.
 8. The assembly of claim 1, wherein thematrix polymer refractive index is 1.4 to 1.75.
 9. The assembly of claim1, wherein the refractive indices of the inorganic filler and the matrixpolymer differ by less than or equal to 0.01 at 25° C.
 10. The assemblyof claim 1, wherein the glazing layer comprises a multiwall sheetcomprising a first wall, a second wall, and ribs disposed therebetween,wherein the first wall has a first wall first surface and a first wallsecond surface, and the second wall has a second wall first surface anda second wall second surface, wherein the thermo-responsive layer isattached to the second wall second surface.
 11. The assembly of claim 1,wherein an air gap is present between the thermo-responsive layer andthe light absorbing layer.
 12. The assembly of claim 1, wherein thematrix polymer has greater than or equal to 85% transparency measuredaccording to ASTM D1003-00.
 13. The assembly of claim 1, wherein thematrix polymer comprises polyesters, polycarbonates, polystyrene,poly(methyl methacrylate), poly(ethyl methacrylate),poly(styrene-co-methyl methacrylate), poly(styrene-co-acrylonitrile),poly(methyl methacrylate-co-styrene-co-acrylonitrile), copolymers ofstyrene, acrylonitrile, (meth)acrylic acids, and (meth)acrylates, andcombinations comprising at least one of the foregoing.
 14. The assemblyof claim 1, wherein the matrix polymer comprises poly(methylmethacrylate), poly(styrene-co-acrylonitrile), or a combinationcomprising at least one of the foregoing.
 15. The assembly of claim 1,wherein the thermo-responsive layer further comprises a plasticizer. 16.The assembly of claim 15, wherein the plasticizer comprises benzoateesters, aliphatic esters, aryl esters of phosphates, and combinationscomprising at least one of the foregoing.
 17. The assembly of claim 16,wherein the plasticizer comprises penterythritol tetrabenzoate,resorcinol bis(diphenyl phosphate), and combinations comprising at leastone of the foregoing.
 18. The assembly of claim 1, wherein the fillercomprises silica, quartz, glass, ceramic particles, gypsum, feldspar,calcium silicate, barium metaborate, mica, clays, magnesium hydroxide,aluminum trihydroxide, Fuller's earth, calcium hydroxide, pyrophyllite,talc, zinc borate, and combinations comprising at least one of theforegoing.
 19. The assembly of claim 1, wherein the filler comprisesmagnesium hydroxide, glass, or a combination comprising one or both ofthe foregoing.
 20. The assembly of claim 1, wherein the filler ispresent in an amount of 5% to 80% by weight.
 21. The assembly of claim1, wherein the thermo-responsive layer, having a thickness of 25 μm to2,500 μm, has greater than or equal to 10% reflection when exposed totemperatures greater than a glass transition temperature of the matrixpolymer.
 22. A method of making an assembly, comprising: forming theglazing layer; forming the light absorbing layer; and forming thethermo-responsive layer, wherein the thermo-responsive layer is betweenthe glazing layer and the light absorbing layer to form the assembly;wherein the thermo-responsive layer comprises a matrix polymer having aglass transition temperature and an inorganic filler, wherein the matrixpolymer comprises 0.5 to 10 weight percent of repeat units derived fromacrylonitrile, based upon a total weight of the matrix polymer, whereinthe refractive indices of the matrix polymer and the inorganic fillerdiffer by less than or equal to 0.05 at 25° C.
 23. The method of claim22, further comprising co-extruding the glazing layer and thethermo-responsive layer.
 24. The method of claim 22, further comprisinglaminating the thermo-responsive layer to a surface of the glazinglayer.
 25. The method of claim 22, further comprising co-extruding thelight absorbing layer and the thermo-responsive layer.
 26. The method ofclaim 22, further comprising laminating the thermo-responsive layer to asurface of the light absorbing layer.
 27. The method of claim 22,further comprising determining a normal working temperature of theassembly, and choosing the matrix polymer so that a difference betweenthe glass transition temperature and the normal working temperature isless than or equal to 20° C.